Creatinine in plasma, serum Women 45-90 µmol/L
Men 60-105 µmol/L
Creatinine varies in relation to muscle mass. In adults, the reference range is unchanged with age as both kidney function and muscle mass decrease with age. The concentration can be 30 % higher hours after a meat-rich meal, and is 30 % higher in the evening than in the morning.
An elevated concentration of creatinine is found when the glomerular filtration rate is reduced (more about glomerular filtration), increased release of creatinine in rhabdomyolysis and ongoing muscle atrophy.
Low concentrations of creatinine are normal after muscle atrophy and reduced liver function.
Sources of error: Some drugs, such as cimetidine, trimethorprim and probenecid, inhibit the tubular secretion of creatinine and increase the concentration in the blood without a reduced GFR.
Read more about creatinine in User handbook on medical biochemistry: